This proposal seeks to develop a new bead-based array technology for simultaneously measuring many proteins and their post-translational modifications in small volumes of cells or biological fluids. Technology of this type is needed to accelerate research in functional genomics by enabling molecular phenotyping of proteins, for many individuals in large populations. Methods will be developed that allow multiplexed immunoassays to be carried out on populations of beads, with each bead type in the population being specific to a particular immunoassay. Basic and clinical applications of this technology will enable careful examination of the molecular basis of cancer and an ability to identify individual characteristics that influence cancer development and progression.